Unless you happen to live near vast stretches of sand, sagebrush, and adobe, chances are you have no idea who Susan Martinez is. That's a pity, because she may be the boldest, savviest vice presidential pick Mitt Romney could make.

Consider Romney’s vulnerabilities. He trails Barack Obama by as many as 56 percentage points among Latinos. Women prefer the president by roughly 20 points. Conservatives still distrust him, and populists in both parties suspect that he’s a vulture capitalist who likes to fire people. New Mexico’s Martinez, the first Latina governor in U.S. history, would solve each of these problems, or help as much as any running mate conceivably could. Within minutes of meeting me in Santa Fe one morning last month, she is speaking fluent Spanish, reminiscing about the .357 magnum she acquired at age 18, and describing her family’s mom-and-pop security business back in El Paso. A scout from Boston would have been very pleased.

Still, it isn’t until a few hours later, when we arrive at Albuquerque’s Mission Avenue Elementary School, that Martinez demonstrates precisely how potent a sidekick she could be. By now, everyone knows that Romney tends to act like a malfunctioning automaton around real people: stiff, preprogrammed, out of sync. Martinez, who has stopped by to read If You Give a Mouse a Cookie, is different. A sturdy 52-year-old with a bronze bob, black jeans, and a cropped black motorcycle jacket, she sits “criss-cross applesauce,” as she puts it, on the floor. She gently restores order every time the kids stand, squirm, squeal, or inch into the circle for a better view of the titular mouse and his hilarious milk mustache. And when she spots one glum little girl sitting off to the side by herself, she makes a point of getting her involved.

“Do you want to help me with my book?” Martinez asks. The girl glances up through her dark bangs. After a few seconds, she nods. “Tell me your whole name,” Martinez says.

“Mackenzie ... Slagle.”

“Well, Mackenzie,” the governor says. “I’m going to read from this book, and sometimes, reading sideways is hard. So I need you to help me.”

Mackenzie smiles—and scoots to Martinez’s side.

It's a small gesture: hardly the sort of thing that would, or should, earn someone a spot on the GOP ticket. Then again, it is also exactly the sort of thing—empathizing, being spontaneous, connecting with another human lifeform—that Romney can never seem to pull off by himself.

The question now is whether Romney, who pledged in January to consider Martinez for his cabinet and “some other positions as well,” will be wise enough to keep his promise—and whether, if offered, Martinez will be ambitious enough to accept.

To thrive in the years ahead, Republicans must do a better job of appealing to three kinds of people: women, Latinos, Westerners. Simply put, the GOP needs to become less of a Mitt Romney party and more of a Susana Martinez party.

The trendlines tell the tale. Over the next 40 years, America's Latino population is projected to triple in size, from 47 million to 133 million, making it the fastest-growing source of potential votes in the country. Unfortunately, Republicans have been shedding Latino support in recent years: last time around, John McCain lost Latinos by 36 percentage points, roughly double George W. Bush's previous margin of defeat. As the GOP veers further and further to the right on immigration—both McCain and Bush supported comprehensive reform, something Romney refuses even to discuss—the chances of closing that gap will only dwindle.

Women are also shying away from Republicans. The main reason Obama was able to beat McCain by 13 percentage points among female voters is that he won unmarried, working, and highly-educated types by double digits—groups that are growing as a percentage of the population. In contrast, the female voters who tend to support Republicans—married, stay-at-home, and non-college-educated women—have been losing market share for decades. If candidates like Romney continue to rely on white, working-class, largely Southern men for most of their support—Democrats are also gaining ground in the burgeoning Sun Belt and Mountain West regions—they will find it harder and harder to compete.

Could Martinez help forestall that fate? She may be dead-set against running with Romney, like she says. (When I ask how she would respond if the presumptive nominee came calling, Martinez cuts me off. “No,” she says. “Absolutely no.”) Or she may be willing, like Joe Biden, to change her mind. At this point, the buzz for Martinez is still building: the Washington Post recently ranked her fifth on its veepstakes list, and GOP strategists such as Mark McKinnon are only beginning to chatter about how “she checks so many boxes Republicans need.” Maybe a few more months of flattery will soften her up. I doubt even she knows for sure.

What I don't doubt is that Martinez has bigger plans for herself, and her party, than her demurrals seem to suggest.

The Mission Avenue event is over, and I’ve just settled into the backseat of the governor’s beige Suburban. She already has a BlackBerry pressed to her ear. I don’t speak Spanish, but she seems to be telling someone how to tend to her garden: water “las vides” for “cinco minutos,” use “la sprinklerita” on “las rositas.” Then she pauses: "Y la Lettie?"

Not many people from Martinez’s modest, minority background end up becoming Republican politicians. That much is obvious. But the most consequential difference between the governor and the GOP’s wealthy, white-bread figureheads may be her relationship with her older sister Leticia, who has cerebral palsy. The challenges of caring for Lettie have shaped Martinez’s personality and her governing philosophy in ways that could counteract the party’s callous, 1-percenter reputation—and resonate with voters, especially women, who tend to recoil from social conservatives.

The Martinez sisters were born in the border city of El Paso, Texas to a secretary mother and boxer-turned-deputy-sheriff father, both of whom grew up in the Segundo Barrio, a notoriously poor, predominantly immigrant part of town. The girls’ great-grandfather, Toribio Ortega, fired the first shots of the Mexican Revolution; their grandfather, Adolfo Martinez, didn’t become a U.S. citizen until 1942, even though he entered the country (lawfully) more than two decades earlier. The Martinezes lived in public housing for years before moving to Thomas Manor, a blue-collar Mexican-American neighborhood surrounded by farmland. It was there that Susana began to watch over Lettie. In elementary school, she would push their twin beds up against the wall and lay on the outside to prevent her sister from falling to the floor while she slept. After their mother died in 2006, Martinez immediately became Lettie’s legal guardian.

When the governor hangs up, I notice that she looks distraught; Lettie, who still lives with her longtime caretaker in the Martinez’s Las Cruces home, couldn’t come to the phone. I ask if she wishes her sister could have moved with her to Santa Fe. “When I go to see her, she says she misses me,” Martinez begins. “But I cannot…” She trails off, and her eyes begin to water. After a moment, she continues. “The other day, Lettie fell on her face. Straight on. A swollen nose, a cut forehead, a swollen lip. So right away I had to go down there and make sure she was OK.”

At 16, Martinez decided not to have children of her own. “In a way, I saw myself as already having raised a child,” she tells me. But because of her experience with Lettie, she has always believed that Washington has a role to play in protecting the most vulnerable Americans—a stance that clashes with the Republican Party’s current cut-at-all-costs mentality. Despite inheriting a $450 million deficit, Martinez managed to wring an additional $6 million in Medicaid money out of the New Mexico legislature during her first year as governor. Her latest budget upped the ante to $45 million. “Lettie is on Medicaid,” Martinez explains. “So I believe in providing services to adults and children who can’t take care of themselves.” The vast majority of national Republicans, including Romney, support Paul Ryan’s Path to Prosperity, which would decimate federal spending on the poor and sick. Martinez thinks they should reconsider. “Sometimes Republicans engage in number-crunching analysis that doesn’t always take the neediest into account,” she tells me. “We have to factor them in before we start proposing these cuts.”

It was the opportunity to advocate for people like Lettie that drew the governor to public service in the first place. Growing up, Martinez was so argumentative that her grandmother nicknamed her “la abogadita,” or the little lawyer. As soon as she graduated from law school, she went to work in Las Cruces as a prosecutor. There, she met detective Chuck Franco, who became her second husband. “I learned to say ‘yes ma’am’ at an early stage,” he recalls. Ten years later, in 1996, Martinez was elected Dona Ana County district attorney with nearly 60 percent of the vote. She went on to win convictions in several high-profile child-abuse and corruption cases, including the infamous “Baby Brianna” Lopez murder, in which Brianna’s father and uncle repeatedly raped, bit, and threw the five-month old from ceiling to floor until she died from brain injuries.

Before the mid-1990s, Martinez had always “attended Democratic meetings and supported Democratic candidates.” But as she prepared to run for D.A., she decided to re-register as a Republican. Martinez has told her conversion story so many times that local politicos can recite it by heart. A couple of Las Cruces conservatives invite her and Franco to lunch. Martinez is wary. But as the Republicans talk, she begins to change her mind. She finds that she agrees with them on issue after issue. She’s pro-welfare reform, having seen the “cycle of dependency” firsthand as a prosecutor. She’s pro-Second Amendment, having carried a gun since she started “securing bingos in parking lots at the Catholic Church” for the family’s security firm as a teenager. (The .357 was so large that “as I walked, I got a nice little bruise on the hip,” she recalls. “But my dad said, ‘You’ll only need to fire once.’”) She’s against higher taxes, having witnessed her father struggle to hire new employees. And she’s opposed to abortion, being a Catholic and all. Afterwards, Martinez turns to Franco in the car. “I’ll be damned,” she says. “We’re Republicans. Now what?”

To me, Martinez’s tale has always seemed a bit too tidy. So as we speed along I-25 in the Suburban, I start to push back: Didn’t you realize you agreed with Republicans on abortion long before this revelatory lunch? And what about welfare reform, the hottest topic in Washington at the time? But Martinez just stares at me. “Nope,” she finally says. “I didn’t pay a whole lot of attention. I registered Democrat because my parents did. They were, we were. There was no thinking behind it. And you’ll hear that over and over here in New Mexico.” Which, of course, is the moral of Martinez’s story, and the reason she repeats it so often: There are a lot more Latinos out there like me, and a lot more of them could be Republicans. But we need to properly persuade them. “As a Hispanic, I grew up this way,” she tells me. “I didn’t suddenly become conservative. It was only the label that changed. ”

At the time, Martinez’s conversion wasn’t especially convenient; Democrats and independents outnumber Republicans in Dona Ana County two-and-a-half to one. But the switch now positions her as a potential party leader: who better to convert Latino Democrats, the thinking goes, than a Latina who used to be a Democrat?

Martinez seems to agree. As we sit down at a local Starbucks, I ask about immigration. It’s a topic she has been reluctant to discuss since winning the Republican primary in 2010, so what comes next is surprising: a battle plan that contradicts nearly everything the GOP has been doing and saying since 2007, Romney’s “self-deportation” strategy included. “‘Self-deport?’ What the heck does that mean?” Martinez snaps. “I have no doubt Hispanics have been alienated during this campaign. But now there’s an opportunity for Gov. Romney to have a sincere conversation about what we can do and why.”

Naturally, Martinez has some suggestions. First, Republicans should remind Latinos that Obama pledged to pass comprehensive immigration reform by the end of his initial year in office, but “didn’t even have the courage to try.” Next, the GOP should outflank the president—on the left—by proposing its own comprehensive plan. “I absolutely advocate for comprehensive immigration reform,” Martinez says, sipping a caramel macchiato. “Republicans want to be tough and say, ‘Illegals, you’re gone.’ But the answer is a lot more complex than that.” Martinez envisions an approach “with multiple levels”: increased border security; deportation for criminals; a guest-worker program for people who want “to go freely back and forth across the border to work”; a DREAM Act-style pathway to citizenship, through the military or college, for children brought here illegally by their parents; and a visa (coupled with a “penalty” or a “tagback”) that allows rest of the illegal population to remain in the U.S. while they follow standard naturalization procedures.

Martinez’s point is not that Republicans should peddle so-called “amnesty.” In New Mexico, she’s taken a lot of heat from Latinos for repeatedly pushing to repeal a state law that allows illegal immigrants to obtain driver’s licenses; she also opposes a standalone DREAM Act, arguing that politicians can’t “fix [immigration] by saying, ‘Here’s the DREAM Act and we’re done. It has to be part of a larger plan.” She simply believes that a more pragmatic approach will help Republicans in the long run, particularly if it’s paired with the sort of issues-based appeal that inspired her to switch parties and a more aggressive campaign to recruit Hispanic candidates for local office. Maybe then the GOP can finally do what she did in her first statewide contest: approach the magic 40-percent mark among Latino voters. That alone would be enough to swing a presidential election.

“We’ve got to stop with the rhetoric,” Martinez says on her way out of Starbucks. “I’m so tired of the rhetoric. ‘Lower taxes,’ you know. ‘More opportunity.’ Da da da. It’s this five-liner of nothingness. There have to be some distinctions for people to latch onto.”

In Washington, pundits are already whispering that Martinez is too much like her 2010 endorser Sarah Palin—an unfamiliar first-term female governor from a far-flung state—for the risk-averse Romney campaign to gamble on.

Superficially, that might be true, and Martinez’s record is not without blemishes. New Mexico progressives accuse her of awarding casino contracts and energy appointments to campaign donors; a mentally ill man named Stephen Slevin was held without a trial for two years at a county prison while she was D.A.; and she was briefly fired in 1992 when her then-boss accused her of bringing in a case her husband had investigated. (Martinez sued, then settled out of court.) Still, since taking office, Martinez has compiled a safe, conservative-friendly resume while methodically avoiding the sort of showy mistakes that sunk Palin in 2008. Even though some initiatives have fallen short, she has managed to cut spending by roughly $150 million without raising taxes, scale back the state workforce by more than 5 percent, ease environmental regulations, preserve tax breaks designed to attract large corporations, eliminate redundant taxes on small businesses, and increase local control over public schools by opting out of No Child Left Behind. “She’s been well-received in the state, but she has not come out a commanding winner in her battles with the Democratic legislature,” says Christine Sierra, a politics professor at the University of New Mexico. “So the jury is still out.”

With Martinez, symbolic gestures have at times seemed to stand in for actual political risk-taking. As soon as she took office, for example, she fired the gubernatorial chefs, grounded the gubernatorial jet, and halved the gubernatorial staff. But the cuts she made, while real, were not nearly enough, on their own, to balance the budget—a feat that ultimately required savings and tax hikes phased in from the previous administration, plus a serendipitous spike in oil revenues. The theory in Santa Fe is that Martinez is more interested in preserving her popularity—with a 60 percent approval rating, she’s one of the country’s most well-liked governors—than in implementing sweeping change. “She hasn’t done a whole lot,” says Joe Monahan, a prominent Santa Fe political blogger and consultant. “Nothing has passed that has pissed a lot of people off. This isn’t big vision stuff. She’s maintaining a competent, minimalist administration so there’s nothing to hang around her neck during the next campaign.”

At Starbucks, Martinez insists that she won’t leave New Mexico anytime soon. “Partly it’s my responsibility to my sister,” she says. “Moving to Washington would be devastating to her. But also, I need to finish this job. I have to deliver the results I promised, because as the first Hispanic female governor, I’m going to pave a path of some kind. I want it to be one that little Hispanic girls will want to follow.”

I nod, but I'm reminded of a story Martinez told me when we first met, earlier today, around her kitchen table at the low-slung governor’s mansion—or “residence,” as she insists on calling it—in the hills north of Santa Fe. When she was 14, a group of teachers at El Paso's Riverside High School invited a handful of promising female students on a weekend retreat. Together, they talked about their hopes and dreams: where do you want to be in five years? where do you want to be in 10 years? When they got to 20 years, Martinez confessed that she was considering a career in politics. “I didn’t know where and at what level,” she recalled. “I didn’t have a whole lot of role models to say, ‘This much is possible, versus this much.’ So I finally said, ‘I think I’d like to be a mayor. I’d like to pull together a city and help do good things.’ And they said, ‘Why stop there?’”